玉米茎剪断力研究

Shearing Force of Maize Stem

玉米秸秆是东北农牧交错地区冷季重要饲料来源。决定玉米秸秆饲料品质的结构部位是茎,茎的剪断力直接反映其物理特征。本文选择四密21、农大3138和登海1号3个玉米品种进行试验。将玉米植株叶片、叶鞘及果穗等去除,按50cm高度分段,研究了玉米茎不同高度处剪断力随时间变化情况。研究结果表明,随着时间推进,茎的剪断力逐渐增大,茎下部的剪断力大于上部。测定剪断力之后的茎,选择登海1号进行化学成分测定,分析剪断力与茎含水量及酸性洗涤木质素、半纤维素和纤维素含量的相关性。结果表明,随着含水量减小,剪断力增大,二者具有负相关关系;剪断力随着酸性洗涤木质素、半纤维素和纤维素含量增加而增大,呈正相关关系。本文研究证明,随着玉米生育期的推进,秸秆用作饲料消化率逐渐下降,尤其在生长后期,消化率迅速下降。

Maize stalk is important forage resource in cold season in ecotone between agriculture and animal husbandry. Quality of stalk forage is determined by physical characteristic of the stem, and shearing force directly indicates physical characteristic of the stem. Three maize cultivars were selected for the experiment in order to utilize maize stalk better. Temporal dynamics of shearing force of maize stem of different height were studied. The results showed that shearing force of the stem increased with maize growth and development. The shearing force of the lower part of stem was larger than that of the higher one. Relationship between shearing force and chemical constituents were also studied by using maize cultivar Denghai 1. Shearing force of maize stem increased with the decrease of moisture content. There was negative correlation between shearing force and moisture content in stem. Shearing force increased with the increase of acid detergent lignin (ADL), hemicellulose and cellulose content. There was positive correlation between shearing force and acid detergent lignin, hemicellulose and cellulose content. It was evident that digestive rate of maize stalk utilized as forage decreased with maize development, especially in the late of maize development.